1. Field of the Invention
This invention involves, in general, the field of medical equipment. More particularly it concerns an optical feedback device for laser surgical devices that controls the amount of white light produced during the burning of biological tissue residues adhering to the laser fiber, while simultaneously discriminating against background white light.
2. Information Disclosure Statement
Contact/non-contact surgical techniques employing laser radiation have been in development for several years. Laser beam manipulator devices have been employed as surgical scalpels as illustrated in, for example, U.S. Pat. No. 3,865,113 of Sharon et al; European Patent Application Serial No. 75912 of Hitachi Ltd. and West German Patent No. 3105297 of Asaki Kogaku Kogyo. Laser devices can also be used to effect blood coagulation or to cauterize as shown by, for example, U.S. Patent No. 3,487,835 of Koester et al.
While it is necessary to precisely control the amount of laser radiation delivered to biological tissue in photo-surgical procedures, it is also necessary to control the rate of burning residue tissue of the optical fiber tip to prevent the fiber from going into a thermal runaway condition.
There currently exists a laser system in which a white light optical feedback controller can control the rate of burning residue tissue by reducing the laser's output power.
While this prior preferred embodiment has proven very effective, it has one serious drawback. In most applications, it is mandatory to have background illumination present (i.e. laprascopic and gynecological applications). Since many of the background illuminators produce similar wavelengths, such as those produced by the burning of the white light tissues, the optical feedback fails to discriminate. Consequently, the lasers erroneously reduces power as if to compensate for burning fiber.
This invention, in addition to this earlier disclosed feedback peripheral, provides discrimination between white light produced by burning of biological tissue and white light from background illumination. This facilitates the use of white light control feedback in the presence of white light background illumination.